Nhung Nguyen Thi, Dutta Avijit, Higginson Ellen, Kermack Leanne, Yen Nguyen Thi Phuong, Phu Doan Hoang, Kiet Bach Tuan, Choisy Marc, Geskus Ronald B, Baker Stephen, Carrique-Mas Juan
Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam.
Cambridge Institute of Therapeutic Immunology & Infectious Disease, University of Cambridge, Cambridge, UK.
JAC Antimicrob Resist. 2023 Jul 22;5(4):dlad090. doi: 10.1093/jacamr/dlad090. eCollection 2023 Aug.
We investigated longitudinally Vietnamese small-scale chicken flocks in order to characterize changes in antimicrobial resistance gene (ARG) content over their life cycle, and the impact of antimicrobial use (AMU) on an intervention consisting of veterinary advice provision.
AMU data and faecal samples were collected from 83 flocks (25 farms) at day-old, mid- and late-production (∼4 month cycle). Using high-throughput real-time PCR, samples were investigated for 94 ARGs. ARG copies were related to 16S rRNA and ng of DNA (ngDNA). Impact of AMU and ARGs in day-olds was investigated by mixed-effects models.
Flocks received a mean (standard error, SE) animal daily dose (ADD) of 736.7 (83.0) and 52.1 (9.9) kg in early and late production, respectively. Overall, ARGs/16S rRNA increased from day-old (mean 1.47; SE 0.10) to mid-production (1.61; SE 0.16), further decreasing in end-production (1.60; SE 0.1) (all > 0.05). In mid-production, ARGs/16S rRNA increased for aminoglycosides, phenicols, sulphonamides and tetracyclines, decreasing for polymyxins β-lactams and genes that confer resistance to mutiple classes (multi-drug resistance) (MDR). At end-production, aminoglycoside resistance decreased and polymyxin and quinolone resistance increased (all < 0.05). Results in relation to ngDNA gave contradictory results. Neither AMU nor ARGs in day-olds had an impact on subsequent ARG abundance. The intervention resulted in 74.2% AMU reduction; its impact on ARGs depended on whether ARGs/ngDNA (+14.8%) or ARGs/16S rRNA metrics (-10.7%) ( > 0.05) were computed.
The flocks' environment (contaminated water, feed and residual contamination) is likely to play a more important role in transmission of ARGs to flocks than previously thought. Results highlight intriguing differences in the quantification of ARGs depending on the metric chosen.
我们对越南小规模鸡群进行了纵向调查，以描述其生命周期内抗菌药物耐药基因（ARG）含量的变化，以及抗菌药物使用（AMU）对一项由提供兽医建议组成的干预措施的影响。
在雏鸡期、产蛋中期和后期（约4个月周期）从83个鸡群（25个养殖场）收集AMU数据和粪便样本。使用高通量实时PCR对样本中的94种ARG进行检测。ARG拷贝数与16S rRNA及DNA纳克数（ngDNA）相关。通过混合效应模型研究AMU和雏鸡期ARG对后续ARG丰度的影响。
鸡群在产蛋早期和后期的平均（标准误，SE）动物日剂量（ADD）分别为736.7（83.0）和52.1（9.9）千克。总体而言，ARG/16S rRNA从雏鸡期（平均1.47；SE 0.10）增加到产蛋中期（1.61；SE 0.16），在产蛋末期进一步下降（1.60；SE 0.1）（均P>0.05）。在产蛋中期，氨基糖苷类、酚类、磺胺类和四环素类的ARG/16S rRNA增加，而多粘菌素、β-内酰胺类以及对多种类型耐药（多重耐药，MDR）的基因则下降。在产蛋末期，氨基糖苷类耐药性下降，多粘菌素和喹诺酮类耐药性增加（均P<0.05）。与ngDNA相关的结果呈现矛盾。雏鸡期的AMU和ARG对后续ARG丰度均无影响。该干预措施使AMU减少了74.2%；其对ARG的影响取决于计算ARG/ngDNA（+14.8%）还是ARG/16S rRNA指标（-10.7%）（P>0.05）。
鸡群的环境（受污染的水、饲料和残留污染）在ARG向鸡群传播中可能比之前认为的发挥更重要的作用。结果突出了根据所选指标对ARG进行量化时存在的有趣差异。
